Production processes of producing chemicals using saccharides as raw materials are employed in the production of various types of industrial raw materials. Currently, saccharides derived from edible raw materials such as sugarcane, starches and sugar beets are industrially used as raw material saccharides. However, in view of an increase in the cost of edible raw materials due to an increase in the world population in the future, or from an ethical point of view that the industrial use of edible raw materials may compete with the use thereof as food, it is a future challenge to develop processes to efficiently produce industrial raw materials from renewable, non-edible resources, namely, cellulose-containing biomasses.
Saccharides contained in cellulose-containing biomass raw materials are embedded within cell walls having a complicated structure. Accordingly, a technique of subjecting a biomass raw material to an alkaline treatment is known to efficiently obtain substances capable of being used as industrial raw materials, directly or indirectly.
For example, to improve the rate of enzymatic hydrolysis of cellulose, a technique is disclosed in which: a cellulose-containing product is subjected to an alkaline treatment by being brought into contact with an aqueous alkaline solution; the treated cellulose-containing product is washed with water and/or an aqueous acidic solution; and then an enzyme treatment is carried out by bringing the cellulose-containing product into contact with an aqueous solution containing a cellulolytic enzyme and a pH buffer, within the range of buffer solution concentration of from 0 to 250 mM (JP 2011-135861 A).
Further, a pretreatment method of carrying out an enzyme treatment of a biomass is disclosed, which method is characterized in that the biomass is supplied into a twin screw extruder; an aqueous solution of an alkaline compound is injected into the extruder while supplying the biomass; kneading the biomass and the aqueous solution in the extruder to allow a reaction to proceed (JP 59-192094 A).
To reduce the cost of producing sugars from a biomass, a method is disclosed in which; an herbaceous biomass or woody biomass is subjected to an alkaline treatment using an alkaline solution; solid-liquid separation is carried out to separate the resulting alkaline treated solution into an alkaline solution and a solid component; the separated alkaline solution is supplemented with an alkaline substance, to be recycled to the alkaline treatment step (JP 2014-23484 A).
Further, to improve the efficiency of enzymatic saccharification and drastically reduce the amount of neutralization effluent, an enzymatic saccharification method of a cellulose-based biomass raw material is disclosed, which method is characterized in that: a slurry containing a cellulose-based biomass raw material which has been cut, crushed, ground, mashed or powdered, calcium hydroxide, and water is prepared to carry out an alkaline treatment of the raw material, followed by solid-liquid separation; solids obtained by the solid-liquid separation, or a mixture of the solids and water is neutralized using carbon dioxide to be adjusted to a pH within the range of from 5 to 8; and an enzymatic saccharification reaction is carried out.
It is also disclosed that hydroxycinnamic acids including ferulic acid and coumaric acid can be obtained from the liquid component obtained by the above-described solid-liquid separation (JP 2013-220067 A).
Hydroxycinnamic acids contain a phenol group and a carboxyl group, and they can be converted into compounds having a styrene skeleton by decarbonation. Hydroxycinnamic acids have been reported to have various pharmacological functions, and it is expected that the application development thereof will be promoted in a variety of fields, leading to the activation of the market and the creation of novel industries. However, a method of efficiently obtaining hydroxycinnamic acids having a high quality from a cellulose-containing biomass is still needed.
It could therefore be helpful to provide a method of efficiently producing hydroxycinnamic acids from a cellulose-containing biomass and a method of producing hydroxycinnamic acids having a high quality from a cellulose-containing biomass.